Previously, many types of cleaning devices and processes have been devised to provide an effective means to clean the ink from a printing press used in lithography or a specific letter press. Many of these processes entail the use of cleaning solvents and liquids in direct contact with the ink roller. Considerable effort has also been displayed in the problems of wear and adjustment of doctor blades that are used to scrape ink from rollers and printing plates.
In most cases, prior art has been concerned with simply the cleaning directly of the roller, or plate, or with a full width doctor blade, of some type, that removes the ink primarily by scraping the surface.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention, however, the following U. S. patents were considered related:
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 4,359,799 Boose Nov. 23, 1982 4,254,709 Arnolds Mar. 10, 1981 4,192,231 Kawakami Mar. 11, 1980 4,151,797 Dunsirn May 1, 1979 3,884,145 Datwyler May 20, 1975 3,468,248 Giori Sep. 23, 1969 ______________________________________
Boose teaches a doctor plate made of an assembly consisting of the doctor knife blade, a back-up blade, and a rigid holder. Each blade is accurately straight and offers the advantage that wear may take place without causing unacceptable alteration of the profile of the scraping, or doctor edge, engaging the printing roll.
Arnolds utilizes a flexible blade with a collecting pan and a mechanism, when in use, includes a locking lever that cooperates with the saddles on the press to lock the ink pan and cleaning blade assembly in position on an angle bracket. Cam means cause movement of the bracket so that the cleaning blade contacts the ink roller. Adjustment is allowed to move the entire mechanism closer to the roller, as the flexible blade wears down through use.
Kawakami discloses an apparatus for automatically washing a doctor blade for removing ink from the ink rollers of a printing press. This is accomplished using a washing vessel with a reciprocating brush that is in contact with the doctor blade and means for spraying washing liquid on the brush device. The blade is cleaned while it is reciprocated and scrubbed by the brush. The doctor blade is made of a thin resilient material of synthetic resins, such as polycarbonate, so that it does not injure the rotating surface of the press roller.
Dunsirn is concerned with maintaining an even and constant pressure of the doctor blade onto the roller. This is accomplished by the utilization of an independently slideable and pivotal support that is spring loaded. The apparatus allows movement of the mounting plate and the blade with pressure adjustments independently at each of four posts.
Datwyler has approached the problem of doctor blade wear by applying a number of individual sections on top of a support element. These individual sections are connected, one with another, and are selectively removable, so that by withdrawing individual sections, the distance between the contact surface and the last section is maintained essentially constant during the progressive wear of the contact surface.
It will be seen that this problem of ink cleaning has been approached in many different and varied ways, however, none have been concerned with removing a selected quality of ink from a predetermined area or by automatic means.